Syncthing sending data to unknown external IP

as I’m having some connection problems recently, I decided to run wireshark today.
I discovered that my PC apparently sent a significant amount of data (~100mb in under half an hour) to an unknown ip address ( which, according to duckduckgo, belongs to ‘’.
sudo netstat -n --program | grep

reveals, that it’s syncthing that is sending that data.

Is that intendet? Am I missing something? I have disabled the usage report and have syncthing running only on my local network.
Edit: Here’s the whois of the ip:

you seem to have relaying enabled, that is a IP of a relay (see for example

MrJeos does, indeed, run a relay. See

Thanks for the quick replys
Reading the changelogs I thought relays are a feature you have to set up yourself, I didn’t realize that public relays will be provided.
I already feared something had taken over the syncthing process (that would at least have explained the weired network issues I have), but fortunately thats not the case.
Thanks again!

Somehow related to this question, therefore asking here and not in a new topic:

Under which circumstances does a Syncthing process connect to a relay? Always (if relays are enable, which is default)? And then announce it as one of its connection IPs?

So if I remove dynamic from every peer on every host, will it still connect to a relay?

Correct: Syncthing will always establish a connection with a relay. Whether another device tries to talk to it via that relay will then depend on whether a connection with that device can be established by other means.

Whether or not a device has dynamic will only control whether that device connects to other devices using global/local discovery. It does not affect how other devices connect to it. Since that device cannot know how other devices will try and connect to it (it doesn’t know that all other devices in the network have had dynamic removed), it has to establish a connection to a relay, in case another device tries to talk to it using that relay.

Ok, this is as I expected then.

Just to be sure: If there is no dynamic involved on any host, the connection to the relay will still be established, but never be used, right? Because removing dynamic removes the option to lookup the host via local/global discovery, thus removing the possibility to find that it’s registered with a relay?

Correct, for now. In the future, I think there will be a way of manually telling Syncthing that you want to connect to device X via relay Y?

I read somewhere (I think in relation to refactoring connections) that you will be able to add a relay address for a device.

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